The present invention relates to a mixing apparatus and, more particularly, to a low cost air powered paint mixing machine.
Numerous configurations of mixing equipment are known which employ various means of motive power as well as varying mechanical motions to induce a mixing process. Among this mixing equipment are low cost mixing devices suitable for use with paints containing volatile solvents. These devices are air powered and usable in environments demanding explosion proof precautions, but they suffer from mechanical motions which are limited to one plane. The motion in these mixing devices is induced by air powered piston/cylinder arrangements which impart no lifting action to the media being mixed and, therefore, have a relatively poor mixing performance in the case of heavy solid type paints.
U.S. Pat. No. 4,834,548 to Tempel et al. discloses an agitating apparatus which employs a mixing motion about a cone having a substantially vertical axis. Although the mixing motion of this apparatus is an improvement over previous devices, the motion has the drawback that heavy solids in the package are not moved upward, since the conical motion is about a substantially vertical axis. Although this patent indicates that good vertical dispersion is achieved since radially outward flow causes a circulation from top to bottom in the package, such satisfactory vertical dispersion appears to be limited to high speeds, that is, preferably at least 1,000 rpm. Mixing apparatus operating at those speeds tends to be less safe than mixers rotating more slowly. In addition, the mixing apparatus disclosed in the Tempel et al. patent requires a stand to support the apparatus and, more specifically, a stand which will allow the drive motor for the apparatus to extend through the stand but be supported above a floor or other supporting surface. Still further, the mechanism of Tempel et al. for providing the conical motion is cumbersome and requires the point of intersection between the rotation axis and motion axis to be spaced inwardly from both the outer and inner apparatus frames.